A typical packet-based communication network can support voice communication sessions between two or more participants. For example, the network could support a voice telephone call or a facsimile transmission by transporting Internet Protocol (IP) packets between a client used by a calling party and a client used by a called party. The quality of service or “QoS” supported in the network often determines whether an acceptable voice communication session can occur across the network. For example, if the network supports only a low quality of service, the participants in a telephone call may notice a substantial amount of disruption in the call.